Lancing device with floating lancet

ABSTRACT

A lancing device including a drive mechanism with a drive spring and a lancet carrier engaged and driven by the drive spring, and further including a lancet with a sharp lancing tip, wherein the lancet floats relative to the carrier and is decoupled from the drive mechanism during at least a portion of a lancing stroke. In one example embodiment the lancet is held in a sled that floats in the carrier, and in another example embodiment the lancet by itself floats in the carrier.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority benefit of U.S. ProvisionalApplication Ser. No. 60/456,927, filed Mar. 24, 2003, which is herebyincorporated by reference herein.

FIELD OF THE INVENTION

[0002] The present invention relates generally to the field of medicalsampling devices, and more particularly to a lancing device having aprecision-guided, high-velocity, low-mass lancet, which is inertiallypropelled and floats within a sliding lancet carrier.

BACKGROUND OF THE INVENTION

[0003] Various lancing devices are known for penetrating the skin of ahuman or animal subject at a lancing site for obtaining a sample ofblood or other body fluids. In general, a typical lancing deviceincludes a housing containing a lancet connected to a spring-drivendrive mechanism, a cocking mechanism for arming or energizing thedrive-spring, and a trigger mechanism for releasing the drive mechanismto complete the lancing operation.

[0004] In order to encourage compliance with a prescribed samplingregimen, for example as in blood glucose sampling by diabetics, it isdesirable to minimize the pain and discomfort resulting from the lancingprocedure. To date, efforts to minimize pain from lancing have largelyfocused on controlling the depth of penetration into the subject's skinat the lancing site. For example, many lancing devices include adepth-control mechanism for varying the depth of penetration, either byadjusting the distance of travel of the lancet tip, or by adjusting theposition of an endcap through which the lancet protrudes during thelancing operation.

[0005] Advances in lancing device technology have, to some extent,reduced the pain associated with the lancing process. However, furtherimprovement in reducing pain and discomfort associated with the lancingprocess is a continuing need. It is to an improved lancing devicemeeting this and other needs that the present invention is primarilydirected.

SUMMARY OF THE INVENTION

[0006] The present invention provides improved lancing devices having alow-mass lancet carried in a carrier. The lancet and carrier arrangementprovides precision guidance of the lancet to minimize rocking andlateral movement of the lancet as it punctures the skin at the lancingsite, minimizing tearing of tissue and resultant pain. The lancet andcarrier are inertially propelled through a high-velocity lancing stroke,with the lancet floating within a bore in the carrier and not in directengagement with the drive mechanism. This results in a lower mass behindthe lancet and a higher lancet velocity during puncturing. Thecombination of low mass and high lancing stroke velocity has been foundto further minimize the pain sensed by a human or animal subject.

[0007] Generally described, the present invention includes a multi-useor disposable lancing device comprising a drive mechanism and a lancet.The drive mechanism includes a drive spring and a carrier that is drivenby the drive spring through a lancing stroke. The lancet is slidinglyengaged by the carrier and, during at least a portion of a lancingstroke, floats relative to the carrier and is decoupled from the drivemechanism. In this way, the carrier engages and drives the lancetthrough a first portion of the lancing stroke, and then the lancet isinertially propelled through a second portion of the lancing strokeafter the carrier is stopped.

[0008] In a first example embodiment, the lancet is received in or is apart of a sled, which in turn is slidably received in the carrier. In asecond example embodiment, the lancet is slidably received directly inthe carrier. In either embodiment, a carrier stop member is providedthat limits the travel of the carrier, but not the lancet/sled, beforethe lancet/sled reaches an extended position. A lancet stop memberlimits the travel of the lancet/sled in the extended position, thelancet stop preferably being a separate structure from the carrier stop.

[0009] In another aspect of the invention, the carrier comprises acarriage that is slidably received in the housing chamber and that has abore that slidably receives the lancet. The carrier further comprisesone or more wings extending outwardly of the housing. In this way, thelancing device can be armed by retracting the wings to a cocked positionwith the carrier in a retracted position. Preferably, one or more strutsextend between the carriage and the wings, and project through one ormore slots in the housing. In this way, after the lancing device isfired but before the lancet reaches an extended position, the carrier isstopped by the carrier struts engaging one or more stop surfaces definedby the housing slots.

[0010] In yet another aspect of the invention, the lancing deviceincludes a cocking mechanism comprising at least one cocking arm and atleast one engagement surface. The cocking arm extends from the sled, thelancet, the carrier, or another component of the drive mechanism. Theengagement surface is positioned on the housing or elsewhere forretaining the cocking arm in a cocked position with the carrier in aretracted position. Also, a trigger mechanism includes a release buttonwith a catch release member that, when the release button is moved,engages the cocking arm and releases the carrier to move to the extendedposition for puncturing skin at the lancing site.

[0011] And in still another aspect of the invention, the lancing devicehas a penetration depth adjustment mechanism comprising an endcap thatrotates relative to the lancing device housing. The lancet includes atleast one engagement surface, and the endcap has a plurality of stopsurfaces that can be selectively aligned with and engaged by the lancetengagement surface to limit forward lancet movement at different depths.In addition, the carriage preferably has a flared proximal section witha flared bore that receives the endcap stop surfaces not aligned withand engaged by the lancet body engagement surface.

[0012] In another aspect of the invention, the present inventionincludes methods of lancing the skin of a subject to obtain a sample ofbody fluid. The methods preferably include driving a lancet or alancet-holding sled through a first portion of a lancing stroke byengagement with a carrier and a drive mechanism; stopping the motion ofthe carrier; and allowing the lancet or a lancet-holding sled tocontinue through a second portion of the lancing stroke after thecarrier is stopped. Preferably, the carrier is stopped by impacting thecarrier, but not the lancet, against a carrier stop surface before thelancet reaches an extended position.

[0013] These and other aspects, features, and advantages of theinvention will be understood with reference to the drawing figures anddetailed description herein, and will be realized by means of thevarious elements and combinations particularly pointed out in theappended claims. It is to be understood that both the foregoing generaldescription and the following brief description of the drawings anddetailed description of the invention are exemplary and explanatory ofpreferred embodiments of the invention, and are not restrictive of theinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0014]FIG. 1 is a perspective view of a lancing device according to afirst example embodiment of the present invention.

[0015]FIG. 2 is a longitudinal cross-section view of the lancing deviceof FIG. 1, with the lancet carrier in a retracted position for cockingthe device.

[0016]FIG. 3 is a longitudinal cross-section view of the lancing deviceof FIG. 1, in an armed state.

[0017]FIG. 4 is a longitudinal cross-section view of the lancing deviceof FIG. 1, with the lancet in an extended position of the lancing strokefor puncturing the skin.

[0018]FIG. 5 is an exploded perspective view of a lancing deviceaccording to a second example embodiment of the present invention.

[0019]FIG. 6 is a front perspective view of a carrier of the lancingdevice of FIG. 5.

[0020]FIG. 7 is a rear perspective view of a carrier of the lancingdevice of FIG. 5.

[0021]FIG. 8 is a front perspective view of a lancet of the lancingdevice of FIG. 5.

[0022]FIG. 9 is a rear perspective view of an endcap of the lancingdevice of FIG. 5.

[0023]FIG. 10 is a longitudinal cross-section view of the lancing deviceof FIG. 5, with the lancet and carrier in a rest position.

[0024]FIG. 11 is a longitudinal cross-section view of the lancing deviceof FIG. 5, with the lancet and carrier in a retracted position.

[0025]FIG. 12 is a cross-section view of the lancing device taken atline G-G of FIG. 11.

[0026]FIG. 13 is a cross-section detail view, Detail “H” of FIG. 12,showing the cocking arm catch being retained in place.

[0027]FIG. 14 is a longitudinal cross-section view of the lancing deviceof FIG. 5, with the lancet and carrier in an activated or firingposition.

[0028]FIG. 15 is a cross-section view of the lancing device taken atline J-J of FIG. 14.

[0029]FIG. 16 is a cross-section detail view, Detail “K” of FIG. 15,showing the cocking arm catch being released for firing.

[0030]FIG. 17 is a longitudinal cross-section view of the lancing deviceof FIG. 5, with the carrier in a stopped position.

[0031]FIG. 18 is a longitudinal cross-section view of the lancing deviceof FIG. 5, with the carrier stopped and the lancet continuing to theextended or puncturing position.

[0032]FIG. 19 is an exploded perspective view of the carrier (in crosssection), lancet, and endcap of the lancing device of FIG. 5.

[0033]FIG. 20 is a perspective view of the carrier (in cross section),lancet, and endcap of FIG. 19, with the endcap in a safety position.

[0034]FIG. 21 is a perspective view of the carrier (in cross section),lancet, and endcap of FIG. 19, with the endcap in a shallow puncturingdepth position.

[0035]FIG. 22 is a perspective view of the carrier (in cross section),lancet, and endcap of FIG. 21, with the lancet fired and in thepuncturing position.

[0036]FIG. 23 is a perspective view of the carrier (in cross section),lancet, and endcap of FIG. 19, with the endcap in a deep puncturingdepth position.

[0037]FIG. 24 is a perspective view of the carrier (in cross section),lancet, and endcap of FIG. 23, with the lancet fired and in thepuncturing position.

[0038]FIG. 25 is a front view of the carrier and lancet of FIG. 19.

[0039]FIG. 26 is a front view of an alternative lancet for use with thecarrier and endcap of FIG. 19.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0040] Referring now to the drawing figures, wherein like referencenumerals represent like parts throughout, preferred forms of the presentinvention will now be described. It is to be understood that thisinvention is not limited to the specific devices, methods, conditions,or parameters described and/or shown herein, and that the terminologyused herein is for the purpose of describing particular embodiments byway of example only. Thus, the terminology is intended to be broadlyconstrued and is not intended to be limiting of the claimed invention.In addition, as used in the specification including the appended claims,the singular forms “a,” “an,” and “the” include the plural, plural formsinclude the singular, and reference to a particular numerical valueincludes at least that particular value, unless the context clearlydictates otherwise. Furthermore, any methods described herein are notintended to be limited to the sequence of steps described but can becarried out in other sequences, unless expressly stated otherwiseherein.

[0041]FIGS. 1-4 show a lancing device 10 according to a first exampleembodiment of the invention. Referring to FIGS. 1 and 2, the device 10includes a housing 12, preferably formed of two inter-engaginghalf-shells 12 a, 12 b. Generally, the housing 12 has a proximal end 14,a distal end 16, and one or more sidewalls 18. In the depictedembodiment, the housing 12 is generally cylindrical and is formed ofplastic and/or other substantially rigid material(s), as for example byinjection molding. It will be understood that other housingconfigurations and materials may be suitably used. In addition, apenetrable foil covering or removable cap (unshown) preferably initiallycovers the opening at the proximal end 14 of the housing 12 to maintainsterility prior to use of the device 10.

[0042] A drive mechanism includes a drive member such as a carrier 20that is slidably mounted to the housing 12. The carrier 20 preferablyincludes a carriage 22 mounted within a channel 24 extending axiallythrough the housing 12, and one or more sleeves or wings 26 extendingoutwardly of the housing 12 and connected to the carriage by a strut 28projecting through a slot 30 in the sidewall 18 of the housing. Thecarriage 22 is preferably engaged within the channel 24 with a closesliding fit to minimize rocking and lateral motion, and to constrain thecarriage to translation along an axial path parallel to direction arrow“a.” The struts 28 preferably slide within the slot 30 with a closesliding fit, further defining the path of translation of the carrier 20and preventing twisting of the carrier within the housing 12. Thesleeves or wings 26 provide a gripping surface for the user to grasp topull back the carrier 20 for cocking the lancing device. As such, thewings 26 may be provided by tabs, collars, finger rests, and othergrasping members. In the depicted embodiment, for example, the wings 26generally conform to the shape of the housing 12 and are in the form ofsleeves that extend a majority of the way around the housing.

[0043] In addition, a proximal hole or opening 32 is formed in theproximal face of the carriage 22 of the carrier 20 for allowing passageof a lancet tip during lancing, as described below. A distal hole oropening 34 is formed in the distal face of the carriage 22 of thecarrier 20 for allowing passage through it of a cocking arm portion ofthe lancet sled, as described below. And a stepped bore 36 (including atrack, channel, etc.) preferably extends axially through the carriage 22of the carrier 20, forming a distally-facing shoulder 38.

[0044] A lancet sled 40 is slidably mounted within the bore 36 of thecarriage 22, and includes a lancet 42 having a sharp lancing tip 44. Thebore 36 is preferably cylindrical, but it may have a square of othercross-sectional shape, if desired, and is axially longer than a body ofthe lancet 42. The lancet 42 may be integrally formed with the lancetsled 40, for example, in a disposable lancing device embodiment. Or itmay be a separate component secured to the sled, as by a friction fitwithin a receptacle of the sled as shown, for example, in a multi-uselancing device embodiment. The sled 40 and lancet 42 preferably have alow mass relative to known lancet and drive mechanisms. A return spring46 is preferably engaged between a flange or projection 47 extendingfrom the lancet sled, and the shoulder 38 of the carrier 20.

[0045] A cocking mechanism preferably comprises at least one cocking arm48 that extends distally from the lancet sled 40 and includes a catchsuch as a barb 50 for engaging an engagement surface such as a flange orshoulder 52 of the housing 12 to secure the sled and carrier arrangementin a cocked position, as shown in FIG. 2. Alternatively, the cocking arm48 may extend from the carrier 20, from the lancet 42 (e.g., inembodiments with the lancet and sled integrally formed as one piece), orfrom another component of the device 10. And the drive mechanismincludes a drive spring 54 that is preferably engaged between thecarrier 20 and the housing 12, for driving the lancet sled 40 andcarrier 20 through a lancing stroke from the cocked position (see FIG.2) to the extended position (see FIG. 4). It will be understood thatother conventional cocking mechanisms may be suitably employed.

[0046] A trigger mechanism includes a trigger or release button 60 thatis preferably mounted at the distal end 16 of the housing 12. Therelease button 60 includes a catch release member such as an inclinedcam face 62 for engagement against a cooperating inclined face 63 orother catch release member of the cocking arm 48. A spring 64 ispreferably provided to bias the release button 60 distally from thehousing 12. When the release button 60 is depressed, the inclined camface 62 engages the cooperating inclined face 63 to release the barb 50from the shoulder 52, thereby firing the device 10 and initiating alancing operation. It will be understood that other conventional triggermechanisms may be suitably employed.

[0047]FIGS. 2-4 depict a sequence of operation of the lancing device 10and a first example method of lancing according to the presentinvention. The lancing device 10 is preferably delivered to the user inan uncocked state, with the drive spring 54 substantially or partiallyrelaxed. The user cocks the device 10 by gripping the housing 12 and thewings 26, and pulling the wings (and thereby the carriage 22 and sled40) distally relative to the housing, into the cocked position shown inFIG. 2, with the drive spring 54 substantially fully compressed.Interaction between the shoulder 38 of the carriage 22 and the flange 47of the sled 40 withdraws the sled distally along with the carrier duringcocking. Engagement of the catch barb 50 with the engagement shoulder 52retains the carrier 20 in a cocked position after the wings 26 arereleased, allowing the carrier to move forward (proximally) within thechannel 24 under the biasing influence of the drive spring 54, as shownin FIG. 3. The user then places the proximal face 14 of the housing 12against the skin at the sampling site of a human or animal subject. Thedevice 10 is fired to complete the lancing operation by pressing therelease button 60, the inclined face 62 of which contacts thecooperating inclined face 63 of the cocking arm 48 and disengages thecatch barb 50 from the engagement shoulder 52. Then the drive spring 54propels the sled carrier 20 and the lancet sled 40 forward to initiatethe lancing stroke.

[0048] When the lancing stroke begins, the sled 40 is retained in aretracted position, toward the distal end of the bore 36 in the carriage22. The sled 40 is retracted in the back of the bore 36 as a result ofthe engagement of the barb 50 and the shoulder 52 holding the carrierback, combined with the forward bias of the drive spring 54 against thecarrier 20 (see FIG. 3). After operating the trigger to fire the device10, the carrier 20 is released and now moves forward under the influenceof the drive spring 54, carrying the lancet sled 40 along with it. Thecarrier 20 and lancet sled 40 move forward together until there is animpact with a carrier stop such as a proximal endwall 70 of the slot 30of the housing 12. For example, the stopping may be caused by thecarrier struts 28 impacting the housing slot proximal endwalls 70, thecarrier wings 126 impacting a protruding structure on the exterior ofthe housing 12, or by other means. Inertia propels the lancet sled 40forward after the carrier 20 stops, with the sled 40 and lancet 42 nolonger being coupled to the carrier 20 or the spring 44 of the drivemechanism.

[0049] The sled 40 slides forward through the bore 36 to the extendedposition, shown in FIGS. 1 and 4, wherein the sharp lancet tip 44 passesthrough the hole 32 and projects a distance beyond the proximal face ofthe housing 12 to puncture the subject's skin at the sampling site. Thelancet sled 40 is stopped in the extended position by a stop member suchas an inside wall of the carriage, the housing, an endcap, or anotherstructure. In any case, the lancet sled stop and the carrier stoppreferably are two separate structures, that is, they are not one andthe same (even though they may both be defined by the endap or thehousing or another component of the lancing device).

[0050] Because the low-mass sled 40 and lancet 42 slide decoupled fromthe drive mechanism (i.e., they “float”) during that portion of thelancing stroke during which the skin is punctured, the subject sensesless impact by the sharp lancet tip 44 against the skin than with knownlancing devices. This significantly reduces the sensation of painrelative to that resulting from lancing with other devices. Afterpuncturing the skin at the sampling site, the return spring 46 retractsthe lancet sled 40 back through the bore 36 of the carriage 22,withdrawing the sharp lancet tip 44 back into the housing 12 to preventinadvertent needle sticks or bloodborne contamination.

[0051] In alternative embodiments, a penetration-depth adjustmentmechanism is provided to allow adjustment of the depth of penetration ofthe lancet tip into the skin of the sampling site. For example, thepenetration-depth adjustment mechanism may be provided by a rotatableendcap on the proximal end of the housing, with the endcap joined to thehousing by a threaded connection permitting the endcap to be extendedand retracted axially relative to the housing by twisting the endcap. Instill other alternative embodiments, the endcap has one or moreadjustably positionable internal stop members that limit the distance oftravel of a lancet.

[0052]FIGS. 5-24 show a lancing device 110 according to a second exampleembodiment of the invention. The lancing device 110 is similar to thelancing device 10 of the first example embodiment. Structuraldifferences include the device 110 combining the carrier and sled intoone component, and the addition of an innovative penetration depthadjustment mechanism, as described below.

[0053] Referring to FIGS. 5-10, the lancing device 110 includes ahousing 112, a drive mechanism, a lancet 142, a cocking mechanism, atrigger mechanism, and an endcap 172. Generally, the housing 112 has aproximal end, a distal end, and one or more sidewalls. The endcap 172preferably includes an opening or passage through which a lancing tipextends for puncturing. In the depicted embodiment, the endcap isseparate from and attached to the housing. Alternatively, the endcap maybe integrally formed with the housing into a single piece without depthadjustment capability, in which case the endcap is essentially anendwall of the housing. As such, the term “endcap” as used hereinincludes any structure at the proximal end of the housing, whetherseparate from or integral to the housing.

[0054] The drive mechanism includes a lancet carrier 120, shown withparticularity in FIGS. 6 and 7. The lancet carrier 120 preferablyincludes a carriage 122 mounted within a chamber 124 extending axiallythrough the housing 112, and one or more sleeves or wings 126 extendingoutwardly of the housing and connected to the carriage by a strut 128projecting through a slot 130 in the housing. The carriage 122translations along an axial path parallel to direction arrow “a.” Aproximal hole or opening is formed at the proximal end of the carriage122 of the carrier 120 for allowing passage of a lancet tip duringlancing, as described below. A bore 136 preferably extends axiallythrough the carriage 122 of the carrier 120. The bore 136 is preferablycylindrical, but it may have a square of other cross-sectional shape, ifdesired. And the drive mechanism further includes a drive spring 154that is preferably engaged between the carrier 120 and the housing 112,for driving the carrier and lancet 142 through a lancing stroke from thecocked position (see FIG. 14) to the extended position (see FIG. 19).

[0055] The lancet 142 is preferably slidably mounted within the bore 136of the carriage 122, and includes a lancet body 143 and a sharp lancingtip 144. The bore 136 is preferably cylindrical, but it may have asquare of other cross-sectional shape, if desired, and is axially longerthan the lancet body 143. Alternatively, the carriage 122 may beprovided by a disc, piston, finger, or other drive member that pushesthe lancet 142, but that does not have a bore for receiving it, so thatthe lancet sliding floats relative to the carriage and in the chamber124. The lancet 42 may be of a conventional type, or it may have specialfeatures for cooperating with the endcap to control the penetrationdepth, as described below. The lancet 142 preferably has a low massrelative to known lancets. A return spring 146 is preferably engagedbetween the lancet body 143 and the endcap 172.

[0056] The cocking mechanism preferably comprises at least one cockingarm and engagement surface for securing the carrier in a cockedposition. In the depicted embodiment, for example, the cocking mechanismhas two cocking arms 148 that extend distally from the carrier 140, eachwith a catch such as a barb 150 for engaging an engagement surface suchas a flange or shoulder 152 of the housing 112, as shown in FIG. 13.

[0057] The trigger mechanism preferably comprises a trigger spring 164and a release button 160. The release button 160 preferably includes acatch release member such as an inclined cam face 162 for engagementagainst a cooperating inclined face 163 or other catch release member ofthe cocking arm 148, as shown in FIG. 16.

[0058] In alternative embodiments, the carrier 120 is included in otherlancing devices in which the lancet fits snugly therein without slidablyfloating therein so that the lancet and carrier do not decouple duringthe lancing stroke. In this way, the carriage of the carrier acts as aconventional lancet holder. Such lancing devices may include the cockingand trigger mechanisms described herein or others. While these lancingdevices do not produce the pain-reducing advantages associated withdecoupling the lancet from the drive mechanism, they neverthelessprovide improved guidance and control of the lancet, which tends toreduce lateral movement and rocking of the lancet and thereby reducepain sensed during puncturing.

[0059]FIGS. 10-18 depict a sequence of operation of the lancing device110 and a second example method of lancing according to the presentinvention. As shown in FIG. 10, the lancing device 110 is preferablydelivered to the user in an uncocked, rest state, with the drive spring54 substantially or partially relaxed. The user cocks the device 110 bygripping the housing 112 and the wings 126, and pulling the wings (andthereby the carriage 122 and lancet 142) distally relative to thehousing, into the cocked position shown in FIGS. 11-13, with the drivespring 154 substantially fully compressed. The return spring 146withdraws the lancet 142 distally along with the carrier 120 duringcocking. Engagement of the cocking arm catch barb 150 with theengagement shoulder 152 retains the carrier 120 in the cocked positionafter the wings 126 are released, as shown in FIG. 13.

[0060] The user then places the proximal face of the housing 112 againstthe skin at the sampling site of a human or animal subject. The device110 is fired to complete the lancing operation by pressing the releasebutton 160, as shown in FIGS. 14-16. When this is done, the inclinedface 162 of the release button 160 contacts the cooperating inclinedface 163 of the cocking arm 148 and disengages the catch barb 150 fromthe engagement shoulder 152, as shown in FIG. 16. Upon operating thetrigger mechanism, the carrier 120 is released and the lancing stroke isinitiated. The carrier 120 is now propelled forward under the influenceof the drive spring 154, carrying the lancet 142 along with it.

[0061] The carrier 120 and lancet 142 move forward together until thereis an impact with a carrier stop such as a proximal endwall 170 of theslot 130 in the housing 112. For example, the stopping may be caused bythe carrier struts 128 impacting the housing slot proximal endwalls 170(as shown in FIG. 17), a proximal face of the carriage 122 impacting adistal face of the endcap 172, or by other means. Inertia propels thelancet 142 forward after the carrier 120 stops, with the lancet 142 nolonger being coupled to the carrier 120 or the spring 144 of the drivemechanism.

[0062] The lancet 142 slides forward through the bore 136 of thecarriage 122 to the extended position, shown in FIG. 18, wherein thesharp lancet tip 144 passes through a hole or opening 132 in the endcap172 and projects a distance beyond the endcap to puncture the subject'sskin at the sampling site. Because the low-mass lancet 142 floatsdecoupled from the drive mechanism of the device 110 during that portionof the lancing stroke during which the skin is punctured, the subjectsenses less impact by the sharp lancet tip 144 against the skin thanwith known lancing devices. This significantly reduces the sensation ofpain relative to that resulting from lancing with other devices. Afterpuncturing the skin at the sampling site, the return spring 146 retractsthe lancet 142 back through the bore 136 of the carriage 122,withdrawing the sharp lancet tip 144 back into the housing 112 toprevent inadvertent needle sticks or bloodborne contamination.

[0063] In addition, a penetration-depth adjustment mechanism may beprovided to allow adjustment of the depth of penetration of the lancettip into the skin of the sampling site. For example, thepenetration-depth adjustment mechanism may be provided by a uniquelyconfigured carrier 120, lancet 142, and endcap 172, as shown in FIGS.6-9 and 19-25. The carrier 120 and the lancet 142 are keyed so that theyfit together in a specific orientation. Preferably, the lancet 142 hasat least one male key member and the carrier 120 has at least one femalekey member, or vice-versa, that cooperate to properly orient the lancet.In addition, the lancet 142 has at least one contact surface and theendcap 172 has a plurality of stop surfaces, or vice versa, foradjusting the puncturing depth of the lancet tip.

[0064] In the depicted embodiment, for example, the lancet body 143comprises four arms 174 in the shape of a “t” with two opposing ones ofthe arms having outer portions 174 a making them longer than the othertwo arms (see FIGS. 8 and 25). The two male key members and two contactsurfaces are formed by the same structure, namely, the two outerportions 174 a of the arms 174 of the lancet body 143. The two arm outerportions 174 a are received in two female key channels 176 in thecarrier 120 to properly orient the lancet 142 (see FIGS. 6, 18, 19, and25). And to provide penetration depth adjustability, the two arm outerportions 174 a selectively engage two sets of three stop surfaces 178 a,178 b, and 178 c (collectively, the “stop surfaces 178”) defined byprotrusions 180 a, 180 b, and 180 c (collectively, the “protrusions180”) extending distally from the endcap 172 (see FIGS. 9, 18 and 19).It will be understood that another number of protrusions 180 and stopsurfaces 178 may be provided, as may be desired for a given application.

[0065] The protrusions 180 are circumferentially arranged relative tothe lancet 142, so that the arms 174 without outer portions 174 a arecircumscribed by the circumferential protrusions, but the outer portionsinterfere with the protrusions when they are in alignment (see FIG. 25).In this way, the endcap 172 can be rotated so that one of the threeprotrusions 180 of each protrusion set aligns with and contacts the twoouter portions 174 a to stop the lancet 142, while the other twoprotrusions of each set are out of alignment with the outer portions anddo not interfere with the lancet. Preferably, the carriage 122 has aflared proximal section 122 a with a flared bore 136 a that receives thetwo protrusions 180 that are not aligned with the outer portions 174 aof the longer arms 174 (see FIGS. 6, 18, and 25). The flared bore 136 ahas a larger diameter or other size-indicating dimension than the bore136.

[0066]FIGS. 20-24 show the use of the adjustment mechanism and a methodof adjusting a lancing device for various penetration depth settings. InFIG. 20, the endcap 172 is positioned with the first/longest protrusions180 a aligned with the arm outer portions 174 a, so that if the lancingdevice is accidentally fired the lancing tip 144 will not extend beyondthe endcap.

[0067] In FIG. 21, the endcap 172 has been rotated (in the direction ofarrow “r”) to a shallow puncturing depth position with thesecond/intermediate length protrusions 180 b aligned with the arm outerportions 174 a. In FIG. 22, the lancet 142 has been fired and is in thepuncturing position, with the second/intermediate length protrusions 180b contacting the arm outer portions 174 a to stop the lancet in theshallow puncturing depth position.

[0068] In FIG. 23, the endcap 172 has been rotated farther to a deeppuncturing depth position with the third/shortest length protrusions 180c aligned with the arm outer portions 174 a. In FIG. 24, the lancet 142has been fired and is in the puncturing position, with thethird/shortest length protrusions 180 c contacting the arm outerportions 174 a to stop the lancet later, in the deep puncturing depthposition.

[0069] It will be understood that the adjustment mechanism can beprovided in alternative forms. In one alternative embodiment, thecarrier 120 and the endcap 172 are the same, but the lancet 242 has abody 243 that generally conforms to the shape of the bore 136 defined inthe carriage 122 and that has outer portions 274 a extending therefrom(see FIG. 26). In another alternative embodiment, the endcap protrusionsthat are not aligned with the outer portions are received in recesses inthe lancet body to avoid movement-limiting interference with the lancet.And in another alternative embodiment, the adjustment mechanism isincluded in lancing device with a lancet that is coupled to the drivemechanism so that it does not float separately therefrom, with thefemale key channels or other structures being defined in the housing oranother component of the lancing device.

[0070] Accordingly, it can be seen that the present invention providesadvantages over other lancing devices. In particular, the presentinvention includes lancing devices in which the drive mechanism isdecoupled from lancet so that, when the skin is pierced, the lancetfloats free of the mass of the drive mechanism. Because of thisdecoupling and free-floating, there is less mass behind the lancet tipwhen impacting the skin, which reduces the pain felt by the user. Inaddition, because the drive spring is decoupled from the lancet when theskin is pierced, this prevents restrikes from spring-induced lancetoscillations. Furthermore, the lancet has a high velocity relative toprevious lancing devices because of the reduced mass/energy ratio fromdecoupling the lancet from the drive mechanism.

[0071] It should be understood that the foregoing relates only toexample embodiments of the present invention, and that numerous changes,additions, modifications and deletions may be made from the exampleembodiments described without departing from the spirit and scope of theinvention as defined by the following claims.

What is claimed is:
 1. A lancing device comprising: a drive mechanismcomprising a drive spring and a carrier driven by the drive spring; anda lancet that is decoupled from the drive mechanism and slidably floatsrelative to the carrier during at least a portion of a lancing stroke.2. The lancing device of claim 1, wherein the carrier engages and drivesthe lancet through a first portion of the lancing stroke, and whereinthe lancet is inertially propelled through a second portion of thelancing stroke after the carrier is stopped.
 3. The lancing device ofclaim 1, wherein the lancing stroke includes the lancet moving from aretracted position to an extended position, wherein the drive mechanismis decoupled from the lancet when the lancet is in the extendedposition.
 4. The lancing device of claim 3, further comprising a carrierstop member that limits the travel of the carrier before the lancetreaches the extended position.
 5. The lancing device of claim 4, whereinthe carrier stop does not limit the travel of the lancet, wherein, afterthe carrier is stopped by the carrier stop, the lancet decouples fromthe carrier and slidably floats relative to the carrier as it continuesmoving toward the extended position.
 6. The lancing device of claim 4,further comprising a lancet stop member that limits the travel of thelancet in the extended position, the lancet stop being a separatestructure from the carrier stop.
 7. The lancing device of claim 1,further comprising a sled that receives or includes the lancet and thatis slidably received in the carrier.
 8. The lancing device of claim 1,further comprising a housing defining an axial chamber, wherein thecarrier comprises: a carriage slidably received in the housing chamber,the carriage defining a bore that slidably receives the lancet; and oneor more wings extending outwardly of the housing, wherein the lancingdevice is armed by retracting the wings to a cocked position with thecarrier in a retracted position.
 9. The lancing device of claim 8,further comprising one or more struts extending between the carriage andthe wings, and projecting through one or more slots in the housing,wherein, after the lancing device is fired but before the lancet reachesan extended position, the carrier is stopped by the carrier strutsengaging one or more stop surfaces defined by the housing slots.
 10. Thelancing device of claim 1, further comprising a cocking mechanismcomprising at least one cocking arm extending from the drive mechanism,and an engagement surface for retaining the cocking arm in a cockedposition with the carrier in a retracted position.
 11. The lancingdevice of claim 10, further comprising a trigger mechanism including arelease button with a catch release member that, when the release buttonis moved, engages the cocking arm and releases the carrier to move to anextended position.
 12. The lancing device of claim 1, further comprisingan endcap with at least a portion that rotates to adjust a penetrationdepth of the lancet.
 13. A method of lancing the skin of a subject toobtain a sample of body fluid, the method comprising: driving a lancetthrough a first portion of a lancing stroke by engagement with a carrierand drive mechanism; stopping the motion of the carrier; and allowingthe lancet to continue through a second portion of the lancing strokeafter the carrier is stopped.
 14. The method of claim 13, wherein thestep of stopping the motion of the carrier comprises impacting thecarrier, but not the lancet, against a carrier stop surface before thelancet reaches an extended position.
 15. The method of claim 14, furthercomprising stopping the lancet in an extended position by impacting thelancet against a lancet stop surface that is separate from the carrierstop surface.
 16. The method of claim 13, wherein the step of allowingthe lancet to continue comprises stopping the lancet after the carrieris stopped.
 17. The method of claim 13, further comprising providing alancing device comprising the lancet and the carrier.
 18. The method ofclaim 17, further comprising providing a sled that receives or includesthe lancet and that is slidably received in the carrier.
 19. A lancingdevice comprising: a housing defining an axial chamber; a lancetmoveable between a retracted position and an extended position; and acarrier comprising a carriage slidably received in the housing chamber,the carriage defining a bore that slidably receives the lancet, one ormore wings extending outwardly of the housing, and one or more strutsextending between the carriage and the wings, and projecting through oneor more slots in the housing, wherein the lancing device is armed byretracting the wings to a cocked position with the carrier in theretracted position and, after the lancing device is fired, the carrieris stopped by the carrier struts engaging one or more stop surfacesdefined by the housing slots.
 20. The lancing device of claim 19,further comprising a cocking mechanism including at least one cockingarm extending from the drive mechanism and defining a catch surface, andan engagement surface defined by the housing for retaining the catchsurface with the carrier in the retracted position, and furthercomprising a trigger mechanism including a release button with a catchrelease member that, when the release button is moved, engages the catchsurface of the cocking arm and releases the carrier to move to theextended position.
 21. A lancing device comprising: a housing; a lancetdefining at least one contact surface; a drive mechanism including adrive member that engages and drives the lancet; and an endcap thatrotates relative to the housing and that has a plurality of stopsurfaces that are selectively aligned with and engaged by the lancetcontact surface to limit forward lancet movement.
 22. The lancing deviceof claim 21, wherein the drive member comprises a carriage that receivesthe lancet and that has a flared proximal section defining a flared borethat receives the endcap stop surfaces not aligned with and engaged bythe lancet body engagement surface.